bubble - audio recorder in html tag

// add the following script to an html widget that also contains html for buttons ( start, stop )
<script>
//Browser compatibility
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia;
window.AudioContext = window.AudioContext || window.webkitAudioContext;
let streamObj;
let config = {
    bufferLen: 4096,
    numChannels: 1,
    mimeType: 'audio/mpeg'
};
let ctx;
let processor;
let microphone;
let holdbuffer = new Array();
let audiodata;
document.querySelector("#btnstart").onclick = startStream; // Wire up start button
document.querySelector("#btnstop").onclick = stopStream; // Wire up stop button

function startStream() {
    ctx = new AudioContext()
    processor =
    ctx.createScriptProcessor(config.bufferLen, config.numChannels, config.numChannels);
    processor.connect(ctx.destination);
      if (navigator.getUserMedia) {
        //Request for the user media
        navigator.getUserMedia(
            { audio: true, video: false },
            onSuccess,
            onErrors
        );
    } else {
        console.log("User media is not supported.");
    }
    console.log("start")
}

let getBuffers = (event) => {
    var buffers = [];
    for (var ch = 0; ch < 1; ++ch)
        buffers[ch] = event.inputBuffer.getChannelData(ch);
    return buffers;
}

function onSuccess(stream) {
    //Play the media stream in the video element
    streamObj = stream;
    console.log(stream.getAudioTracks()[0].getSettings());
microphone = ctx.createMediaStreamSource(stream);
microphone.connect(processor);
processor.onaudioprocess = function(event) {
    var tdata = getBuffers(event);
    holdbuffer.push(tdata);
console.log(tdata[0].length)
};
}

function onErrors(error) {
    //Handle the permission denied error in Chrome and 'Starting video failed' error in Firefox
    if (error.name == "PermissionDeniedError" || error == "Starting video failed") {
        alert("Media might already be in use");
    } else { //Handle all other errors
        console.log("error: ", error);
    }
}

function stopStream() {
     streamObj.getAudioTracks()[0].stop();
    ctx.close();
    processor.disconnect();
    audiodata = new Blob(holdbuffer, {type : 'audio/pcm'});
    console.log("stop " +audiodata.size)
}
</script>